Vertical distribution of the phytoplankton in the water column in the Baffin Bay

Presentation of the main results.

Context

This project aims at exploring how various metrics/proxies can give insights on the vertical distribution of the phytoplankton biomass in the water column using the data measured during the Green Edge oceanographic cruise conducted in the Baffin Bay in 2016. Four main indicators were considered to get insights about the phytoplankton biomass in the water column:

1. Fluorescence
2. Pigments
3. Particle beam attenuation coefficient (CP)
4. Particle backscattering coefficient (bbp)

Most of the data is presented as a function of open water days (OWD) that were calculated in Randelhoff et al. (2019). The first graph shows the OWD of each station.

Fluorescence

This section shows the vertical distribution of phytoplankton based on fluorescence.

Fluorescence from the CTD

Using boxplots can be one interesting alternative way to present the data. For example, I have divided the CTD fluorescence data presented in the above graphic into ice-free/ice-covered and above/below the 0.1 isolume.

Fluorescence from the MVP

Note that because the MVP is measuring continually, there are no stations associated with each measurement. This is why that the MVP data is not presented as a function of OWD.

Pigments

These graphs were made using the pigments data from the rosette. Pigments were summed into two groups:

1. Photoprotection pigments
2. Accessory pigments

Particle beam attenuation coefficient (CP)

CP from the CTD

The CP visualization based on the CTD can be seen above. There is a clear relationship between fluorescence and CP as seen below.

CP from the MVP

Particle backscattering coefficient (bbp)

bbp from the hydroscat

These graphs show bbp at six different wavelengths measured by the hydroscat.

Primary production

in-situ primary production

Visualization of in-situ primary production based on the data from Patrick Rimbault.

Estimated primary production

A lot of work has been done for this section. The goal was to calculate primary production based on photosynthetic parameters. Note that estimation of daily primary production was calculated between the surface and the isolume depth corresponding to the 0.1 mol photons \(m^{-2} d^{-1}\).

This is the list of data used to estimate primary production:

1. Photosynthetic parameters
2. Incident PAR calculated from SBDART.
3. PAR transmittance in the water column calculated from the C-OPS.
4. Chla from the CTD.

The next graph shows these intermediate parameters used to estimate primary production for four different stations.

Finally, we can visualize estimated primary production as a function of OWD.

Comparing in-situ and estimated primary production

Interestingly, we can see that there is a good relationship between measured and estimated primary production (considering that both in-situ and estimated values are independent). We can also observe that at low values, estimated primary production is somehow underestimated compared to in-situ measurements.

To get more insights, I have divided the data into three main categories: Amundsen, barge and ice-covered stations.

Particulate organic carbon (POC)

Phytoplankton absorption

Maybe we could use absorption information to get some additional insights.

Vertical profiles

This graph shows the vertical profiles of phytoplankton absorption at 440 nm. It seems that open water stations have subsurface maximum more apparent than the profiles of the ice-covered stations.

Spectral profiles

By looking at the spectral profiles, we can also notice that there are indeed differences in the water column.

Finally, I have averaged the spectral profiles in four categories. I think these can be seen as end-members spectra.